Considerable resources have been invested over the years in finding ways to utilize "waste" materials. Thus, large amounts of materials such as glass, paper, and aluminum which would likely have ended up in a land fill in past years, are now likely to be re-used in the manufacture of new products.
Utilizing particulate waste materials comprising small particles (sometimes hereinafter simply "particulates") tends to be especially problematic. The small size of the particles of a particulate may make it impossible or impractical to transport the particulate and/or use the particulate. Examples having such small particles include fly or bottom ash generated from combustion of fuels in power generation, heating plants, and industrial boilers; paper mill sludge generated by paper production; cement kiln dust generated by the manufacture of cement; iron and steel fines from steel mills; and dust and other particulates originating from unpaved roads.
Finely divided particulates may also pose a serious risk to the environment and the health of people and animals. Inhalation of such particulates may cause suffocation or injury. Such particulates may create a risk of explosion. When being transported, particulates escaping from a carrier vehicle may be a risk to nearby vehicles or property. If found on the surface of a road, finely divided particulates in the form of dust can reduce traction and decrease visibility.
One method for utilizing particulate waste materials involves using agglomeration agents to increase particle sizes to usable diameters. A variety of materials are currently used as agglomeration agents including liquid silicates, starches, adhesives, and hydraulic cements. Agglomeration might be accomplished by agglutination, flocculation, chemical binding, and/or adhesion.
Although agglomeration of particles is known, the use of known agglomeration agents may be unsatisfactory for a number of reasons. One reason is that the agglomeration agent itself comprises materials to be conserved. Another is that it may be economically impractical to utilize known agglomeration agents. The agent itself may be too expensive, or have too much utility elsewhere, to justify its use as an agglomeration agent. Thus there is a continuing need to identify new agglomeration agents.
Some waste materials, in addition to having no known utility, are difficult to dispose of. Such materials include leftover surface coatings such as paints from painting and construction. As an example, latex paint waste is increasingly being prohibited from landfills due to restrictions on disposal of liquid wastes.
In general, even for other materials than those previously described, disposal in land fills is undesirable due to the limited capacity of existing land fills and the risk posed in maintaining land fills. Thus, there is a continuing need to find ways to dispose of waste materials other than by dumping them in a land fill.